math ToolUpdated 2026-09-19
Ratio Calculator
Solve proportions in the form A : B = C : D. Enter three known values to compute the missing term.
Formula & Mathematical Methodology
D = (B × C) ÷ A
Cross-multiplication states that A × D = B × C. Solving for D yields D = (B × C) / A.
How to Use This Ratio Calculator
- Enter known values A, B, and C.
- The calculator cross-multiplies and solves for D.
Step-by-Step Worked Example
Scenario: 4 : 6 = 10 : D
1. Multiply B and C: 6 × 10 = 60
2. Divide by A: 60 ÷ 4 = 15
Final Calculated Result: 15
What Does Your Result Mean?
Provides the exact proportional fourth term maintaining parity between both ratios.
Common Practical Applications:
- Aspect ratio scaling for digital screens
- Map scale conversions
- Chemical dilution recipes
Important Limitations & Assumptions:
- A cannot be zero.
Frequently Asked Questions
What is a proportion?
A proportion is an equation stating that two ratios are equivalent.
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